Physical dependence refers to a state resulting from habitual use of a drug, where negative physical withdrawal symptoms result from abrupt discontinuation. it is to be distinguished from drug dependency which is characterised by a psychological craving for a drug.[1] From the point of view of the dependent person, "dependence is duress," argues addiction researcher Griffith Edwards.[2]

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Increased heart rate and/or blood pressure, sweating, and tremors are common signs of withdrawal. More serious symptoms such as confusion, seizures, and visual hallucinations indicate a serious emergency and the need for immediate medical care. Alcohol, benzodiazepines, and barbiturates are the only commonly abused substances that can be fatal in withdrawal. Abrupt withdrawal from other drugs, such as opioids or psychostimulants, can exaggerate mild to moderate neurotoxic side effects due to hyperthermia and generation of free radicals[3], but life-threatening complications are very rare.

Treatment for physical dependence depends upon the drug being withdrawn and often includes administration of another drug, especially for substances that can be dangerous when abruptly discontinued. Treatment usually requires the initiation and then tapering of a medication that has a similar action in the brain but a longer half-life.

Physical dependence is different from drug addiction. The latter is often characterized by a psychological need for a drug, while the former can often be the result of legal, long-term use of medicine.[4]